NPE in com.parse.ParseKeyValueCache.saveToKeyValueCache

[j-koenig]

Hey,
we are using the Parse Android SDK in version 1.10.1 in our app and we are experiencing some NPEs in our current live version. There is no way to reproduce it reliably but i will attach a stacktrace. The crash does not seem to be platform specific or device specific.

java.lang.RuntimeException: An error occured while executing doInBackground()
    at android.support.v4.content.ModernAsyncTask$3.done(ModernAsyncTask.java:137)
    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
    at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
    at java.util.concurrent.FutureTask.run(FutureTask.java:242)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.NullPointerException: Attempt to get length of null array
    at com.parse.ParseKeyValueCache.saveToKeyValueCache(ParseKeyValueCache.java:141)
    at com.parse.NetworkQueryController$1.then(NetworkQueryController.java:70)
    at com.parse.NetworkQueryController$1.then(NetworkQueryController.java:63)
    at bolts.Task$14.run(Task.java:784)
    at bolts.BoltsExecutors$ImmediateExecutor.execute(BoltsExecutors.java:105)
    at bolts.Task.completeImmediately(Task.java:775)
    at bolts.Task.continueWith(Task.java:574)
    at bolts.Task.continueWith(Task.java:585)
    at bolts.Task$12.then(Task.java:679)
    at bolts.Task$12.then(Task.java:667)
    at bolts.Task$15.run(Task.java:825)
    ... 3 more

[parse-github-bot]

Thank you for your feedback. We prioritize issues that have clear and concise repro steps. Please see our Bug Reporting Guidelines about what information should be added to this issue.

Please try the latest SDK. Our release notes have details about what issues were fixed in each release.

In addition, you might find the following resources helpful:

• Documentation: https://www.parse.com/docs
• Google Groups: https://groups.google.com/forum/#!forum/parse-developers
• Stack Overflow: http://stackoverflow.com/tags/parse.com

[wangmengyan95]

Hi @j-koenig , thanks for opening this issue. For your case, we want to know do you use Local Datastore feature in your app?

[j-koenig]

Hi @wangmengyan95 , no Local Datastore is disabled for our app.

[wangmengyan95]

Hi @j-koenig, another reason we can think of is we use cacheDir/ParseKeyValueCache as the cache folder for the ParseKeyValue cache. We create this folder when you call Parse.initialize(). So in your app, have you ever touched this folder or cleaned the cacheDir manually?

[julianshen]

We also meet the same issue (1.9.4). It might not be safe if the dir is only created at Parse.initialize(). If user clear cache in Settings and switch back to application, it might causes problem. (That's how we reproduce this). Suggest to add codes to re-initialize it if listFiles() returns null.

[j-koenig]

Hey @wangmengyan95 and @julianshen thanks for your posts. I checked the whole app for an access of the cacheDir but I couldn't find any. So I'm pretty sure that we don't touch or clean the cacheDir manually.

With @julianshen s hint I was able to reproduce the crash:

1. Open the app for the first time -> ParseKeyValue cache gets initialized
2. Do stuff in the app -> entries will be generated in the ParseKeyValue cache
3. Close the app, go to settings, clear app cache
4. Reopen the app, do stuff -> crash

Since this isn't a completely unusual scenario and we as app developers cannot prevent the user from doing this: wouldn't it be best practice to reinitialize the the ParseKeyValue cache if the cacheDir has been cleared?

[grantland]

This looks to be an actual bug.

@wangmengyan95 Could you also check any other place we use the cache dir?

[wangmengyan95]

@julianshen @j-koenig , thanks guys, I think this is a valid bug since we can not prevent users to clear the cache dir.
@grantland , I will check where we use the cache dir.

[wangmengyan95]

#141

[j-koenig]

👍